Failed to establish connection with report server

When I configure SQL Reporting Services 2008 for integration with SharePoint 2010, I encounterred an error, that is 'Failed to establish connection with report server. Verify the server URL is correct or review ULS logs for more information. Product area:
SQL Server Reporting Services, Category: Configuration Pages '. After reading the below article, I re-created the Report DB and set the report server mode from
Native Mode to SharePoint Integrated Mode, and the error disappearred. So, when you run into such error or related errors, just check the following 6 steps to see if you do some wrong actions.

There are only 6 main steps to achieve this task assuming you already have an instance of SQL Server
Reporting
Services and SharePoint 2010.

I had created this starting from a clean installation of SQL
Reporting Services so this guide will discuss the
steps on configuring your SQL
Reporting
Services 2008 for integration with
SharePoint 2010.

Step 1: Configuring SQL Reporting
Services – Web Service URL

Simply go to Reporting
Services Configuration Manager and choose Web
Service URL and populate the following needed information. The fields are named properly so I guess there is no need for further explanation. What this does is that it configures the IIS for you depending on what Virtual Directory names
you had declared.



Step 2: Configuring SQL Reporting
Services – Create a Report Database

Same here, fields need no further explanation except for one which is Native Mode and
SharePoint Integrated mode which I will explain below.

Choose create a database or if you already have one choose an existing one. For this example, we will create a new one:



Connect to the database where you want your Report Data to be stored:



Give it a Name and a Report Server Mode.

With SharePoint Integrated Mode the report RDLs are stored on
SharePoint and not in the Report Database. For this instance, we will use the
SharePoint Integrated Mode:



Specify the credentials that the report server will use to connect to the database.



Review your configuration.



Then wait while it's configured.

Step 3: Configuring SQL Reporting
Services – Create a Report Manager URL

What this does is that it configures the IIS for you depending on what Virtual Directory names you had declared.



That’s it. At this point, your report server is configured for
SharePoint Integration 2010.

Step 4: SharePoint Integration Configuration –
Reporting Services Integration

Simply go to SharePoint 2010 Central Administration, then General Application Settings, then choose
Reporting
Services Integration.



Now populate the fields using the Web Service URL you had configured a while ago on Step 2 of this guide.



Once done, you will see the Activation State message.

Step 5: SharePoint Integration Configuration – Add a Report Server to the Integration

Now add the report server by putting the Server Name and the Server instance.



At this point it's all done, all you have to do now is try it out.

Step 6: Verify by Checking the Server and Uploading a Report

To verify if it's now integrated, go to Site Settings on your
SharePoint Site, then Site Collection Features.





Check if the Report Server Integration Feature is Active, if not just click activate:



Now try to use the SQL Server Reporting
Services Webpart:





Or you can also upload a report from a library.



That's it, so simple!

Reference URL：http://www.codeproject.com/Articles/88285/Integrating-Sharepoint-2010-and-SQL-Reporting-Serv.aspx